As military targets, such as aircraft, become faster and more maneuverable, they become more capable of avoiding or outrunning the projectiles that are fired to intercept them. The military, therefore, to meet its mission, must improve its gun systems by reducing the time required for a projectile to reach its target from the instant of launch. Numerous techniques are used in laboratories to launch projectiles at very high velocity. Heretofore, these methods have required excessively large or short lived, expendable launchers which are not conducive to conversion to military use. One of the most common and highly developed of these laboratory launchers is the two stage light gas gun.
The commonly known two stage launcher has a gas pump tube and launch tube which are longitudinally disposed. Within the gas pump tube is a piston separating the propellant and the gas. The propellant pumps the piston against the gas behind the projectile in the launch tube. When compressed sufficiently, the gas ejects the projectile from the launch tube. This tandem arrangement of two tubes is excessively long and results in projectile placement at a point far removed from the breech of the gun.